186 research outputs found
The autonomy and importance of the towns in the process of state formation in the Low Countries:The examples of Antwerp and Amsterdam
Surface nanoscale axial photonics: Robust fabrication of high quality factor microresonators
Recently introduced Surface Nanoscale Axial Photonics (SNAP) makes it
possible to fabricate high Q-factor microresonators and other photonic
microdevices by dramatically small deformation of the optical fiber surface. To
become a practical and robust technology, the SNAP platform requires methods
enabling reproducible modification of the optical fiber radius at nanoscale. In
this Letter, we demonstrate super-accurate fabrication of high Q-factor
microresonators by nanoscale modification of the optical fiber radius and
refractive index using the CO2 laser and the UV excimer laser beam exposures.
The achieved fabrication accuracy is better than 2 angstroms in variation of
the effective fiber radius
Bioconversion of (+)- and (-)-alpha-pinene to (+)- and (-)-verbenone by plant cell cultures of Psychotria brachyceras and Rauvolfia sellowii
This work describes the bioconversion of (-)- and (+)-alpha-pinene
(2,6,6-trimethyl-bicyclo[3.1.1]hept-2-ene), targeted at the production
of (-)- and (+)-verbenone (4,6,6-trimethyl-bicyclo (3.1.1)
hept-3-en-2-one), respectively, using Psychotria brachyceras and
Rauvolfia sellowii cell suspension cultures. P. brachyceras showed
selectivity to (-)-alpha-pinene with 80.9% conversion (relative
integrated area gas chromatography-mass spectrometry (GC-MS)) of
(-)-verbenone in 10-day-incubation, whereas R. sellowii was able to
convert both pinene enantiomers (37.6% conversion of (-)-verbenone in
7-day-incubation and 32.2% conversion of (+)-verbenone in
10-day-incubation). In both systems trans-verbenol was formed as main
product and then slowly biocatalyzed to verbenone. Verbenone were also
present among the autoxidation products during control experiments, but
in much lower amounts and accompanied by several by-products,
highlighting the usefulness of the biotransformation process
YBa2Cu3O7 and Nb NanoSQUIDs for the Investigation of Magnetization Reversal of Individual Magnetic Nanoparticles
We report on the fabrication, performance and application of sensitive YBa2Cu3O7 (YBCO) and Nb nanoSQUIDs to magnetization reversal measurements of individual magnetic nanoparticles. The YBCO SQUIDs are based on grain boundary Josephson junctions and are patterned in a single layer of epitaxially grown YBCO films by Ga focused ion beam milling. The Nb SQUIDs contain sandwich-type Josephson junctions with normal conducting HfTi barriers; they are fabricated with a multilayer technology that includes patterning by e-beam lithography and a combination of milling techniques and chemical-mechanical polishing. Due to the small inductance of the SQUID loops, ultralow white flux noise at 4.2 K can be achieved, which yields spin sensitivities of down to a few Bohr magnetons per unit bandwidth for a magnetic nanoparticle placed at 10 nm distance to the SQUID loop
First results from stimulation assessment and monitoring of the 426°C geothermal well RN-15/IDDP-2 (H2020-DEEPEGS project)
The RN-15/IDDP-2 deep geothermal well of the DEEPEGS EU project on the Mid-Atlantic ridge at Reykjanes, Iceland, is a unique site for geothermal research. With a bottom hole temperature of approximately 426°C, it is one of the hottest geothermal wells ever drilled aiming for fluids at supercritical condition. Consequently, down-hole measurements are reliable to a depth of about 3.5 km, only. Pressure and temperature condition in the reservoir can be inferred using the newly developed wellbore simulator WellboreKit.
Due to complete fluid loss, the well has been drilled at flow rates that reach hydraulic stimulation condition. After the drilling, the well was stimulated further by applying different concepts ranging from high flow rate hydraulic stimulation to long-term but low flow rate hydraulic stimulation to increase the reservoir performance at around 4.6 km depth. Thermo-hydro-mechanically coupled numerical modelling was performed to predict the performance response and thus, develop a well stimulation schedule. Processes related to drilling and stimulation are monitored using seismic and magnetotelluric methods to characterize and understand the processes ongoing during injection
Advancing knowledge on the costs and benefits of sustainable soil fertility management in Maharashtra and Madhya Pradesh /India
The majority Indian rural households depend for their livelihoods on the productivity of the farming systems. Almost universally, the yield gap between potential and achieved productivity is large, water and nutrient use efficiency is low and land degradation can be widely observed (Lobell et al. 2009, Conklin & Stilwell 2007). Also in the States of Maharashtra and Madhya Pradesh livelihoods of around 65% of the rural population depend on agriculture and related activities. A large share of them are smallholder farmers with often low and unstable crop and livestock productivity. At the same time, land degradation is a major concern also driven by changing cropping patterns. Overall, there has been a steady decline in the area under water efficient crops like groundnut, pigeon pea and other millets. The area under rice and cotton has increased in the recent decades mainly owing to the (over)exploitation of groundwater. Besides, there is indiscriminate use of chemical fertilizers and unbalanced-application of nutrients. Policies subsidizing inorganic fertilizers, particularly N and P also encourage the farmers to rely more strongly on inorganic fertilizer than on organic ones..
Photoelasticity of crystalline and amorphous silica from first principles
Based on density-functional perturbation theory we have computed from first
principles the photoelastic tensor of few crystalline phases of silica at
normal conditions and high pressure (quartz, -cristobalite,
-cristobalite) and of models of amorphous silica (containig up to 162
atoms), obtained by quenching from the melt in combined classical and
Car-Parrinello molecular dynamics simulations. The computational framework has
also been checked on the photoelastic tensor of crystalline silicon and MgO as
prototypes of covalent and ionic systems. The agreement with available
experimental data is good.
A phenomenological model suitable to describe the photoelastic properties of
different silica polymorphs is devised by fitting on the ab-initio data.Comment: ten figure
Initial Characterization of the FlgE Hook High Molecular Weight Complex of
The spirochete periplasmic flagellum has many unique attributes. One unusual characteristic is the flagellar hook. This structure serves as a universal joint coupling rotation of the membrane-bound motor to the flagellar filament. The hook is comprised of about 120 FlgE monomers, and in most bacteria these structures readily dissociate to monomers (∼ 50 kDa) when treated with heat and detergent. However, in spirochetes the FlgE monomers form a large mass of over 250 kDa [referred to as a high molecular weight complex (HMWC)] that is stable to these and other denaturing conditions. In this communication, we examined specific aspects with respect to the formation and structure of this complex. We found that the Lyme disease spirochete Borrelia burgdorferi synthesized the HMWC throughout the in vitro growth cycle, and also in vivo when implanted in dialysis membrane chambers in rats. The HMWC was stable to formic acid, which supports the concept that the stability of the HMWC is dependent on covalent cross-linking of individual FlgE subunits. Mass spectrometry analysis of the HMWC from both wild type periplasmic flagella and polyhooks from a newly constructed ΔfliK mutant indicated that other proteins besides FlgE were not covalently joined to the complex, and that FlgE was the sole component of the complex. In addition, mass spectrometry analysis also indicated that the HMWC was composed of a polymer of the FlgE protein with both the N- and C-terminal regions remaining intact. These initial studies set the stage for a detailed characterization of the HMWC. Covalent cross-linking of FlgE with the accompanying formation of the HMWC we propose strengthens the hook structure for optimal spirochete motility
Physicochemical properties of frozen tortillas from nixtamalized maize flours enriched with β-glucans
SCREENING OF WILD FRUIT TREES WITH GASTROPROTECTIVE ACTIVITY IN DIFFERENT EXPERIMENTAL MODELS
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